What it is:
Cortisol is a hormone related to stress and adrenal gland function.
Why it is beneficial to breeders:
Helps evaluate adrenal health and hormone balance
Useful for identifying conditions like adrenal dysfunction
Supports investigation of ongoing illness, lethargy, or weakness
Assists in understanding abnormal stress responses
When breeders should use it:
When a dog has unexplained weakness, lethargy, or appetite changes
If adrenal disease is suspected
As part of testing recommended by a veterinarian
When long-term hormone imbalance is a concern
 
To summarize:
Cortisol: A blood test that helps evaluate stress hormone levels and adrenal gland function.